You can check your email address to see if it has been potentially compromised by hackers at HackNotifier. This doesn't necessarily mean that your personal email account has been hacked, but that a website or an account that you supplied your email address to register or access may have. Which also stresses the importance of using different passwords for each site. You can find a more detailed article here.

I discovered that one of my GMAIL accounts, which I use to register on websites and forums, but not for work, financial or friends related, was part of a group which was hacked including Gizmodo. Which may explain why I began receiving more spam in that particular email account.

I use the free open source KeePass Password Safe on all my computers and smartphones, and use Dropbox to sync/backup the encrypted database. So any changes made from one computer or from my smartphones is reflected on all. You can store any type of info. in Keepass, not just passwords.

Another very good free password manager is Lasspass which will also sync between all your computers and portable devices.